There has been a continual need for efficiently sintering nonoxide ceramics, particularly those that are suitable for high-hardness and high temperature applications, such as are required for drill and tool bits and for ceramic armor. Boron carbide is an excellent lightweight material for ceramic armor and high-wear applications. However, the material does not sinter well, requiring temperatures over 2200 C for densification with or without hot-pressing.
Microwave sintering of boron carbide at 2000.degree. C. is described in a paper by J.D. Katz, R.D. Blake, J.J. Petrovic and H. Sheinberg, Microwave Sintering of Boron Mat. Res. Soc. Symp. Proc., Vol. 124, pp 219-226, 1988.
Examples of methods for densifying boron carbide are described in U.S. Pat. No. 4,195,066 which describes the introduction of carbon additives necessary for pressureless sintering of boron carbide and U.S. Pat. No. 4,320,204 which describes the utilization of silicon carbide/aluminum composites.